Piercing and expanding mill.



PATENTED JAN. 20, 1 903.

' J. H. NICHOLSON. PIERGING AND EXPANDING MILL.

APPLICATION FILED IAB JI G, 1900.

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No. 718,723. PATENTBD JAN. 20, 1903.

' J. H. NICHOLSON.

PIERGING AND EXPANDING MILL.

APPLICATION FILED MAR. 15, 1909. I

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JOHN H. NICHOLSON, OF PITTSBURG, PENNSYLVANIA, ASSIGNOR TO THE STANDARD SEAMLESS TUBE COMPANY, A CORPORATION OF PENN- SYLVANIA.

PIERCI'NG AND EXPANDING MILL.

SPECIFICATION formingpart of Letters Patent No. 718,723, dated January 20, 1903. Application filed March 15, 1900. Serial No. 8,738. (No model.)

To all whom, it may concern:

Be it known that 1, JOHN H. NICHOLSON, engineer,of Bellfield avenue,Pittsburg,Pennsylvania, have invented certain new and useful improvements in piercing and expanding mills for the manufacture of tubular or partially-tubular bodies in a heated state by the use of oblique or skewed rolls, of which the following is a specification.

In the practical use of piercing and expanding mills operating under the Mannesmann processes difficulty has been frequently experienced in properly determining and balancing thefeeding efiects when the two rolls are unsymmetrically designed or unsymmetricallymounted. By rolls I mean also to include disks and various rolling bodies.

In my earlier patent, No. 628,024, dated July 4, 1899, I have set forth one manner of arranging feed relations for two symmetrically-placed'similar rolls. The present invention seeks to accomplish a slight holding down of the billet against the guide by a slightly,unsymmetrical disposition of oblique rolls, while at the same time preserving in other respects substantially the advantages to be had by symmetrically-placed rolls.

In order to explain my invention simply, it will be best first to consider the geometrical relations between rolls symmetrically disposed about a pass. \Vhen so disposed, a plane may be drawn through the axial line of the pass and parallel with the axes of both rolls. chosen parallel with the axis of both the rolls and the pass. Furthermore, when the axes of the rolls are projected onto such base-plane they form equal angles with the axis of the pass. When, however, the axes are not symmetrical, such a base-plane may be chosen in respect to the pass and one of the rolls, since a plane can always be drawn parallel with the two given lines however placed; but the axis of the other roll will not be parallel with such base-plane, and yet such roll where it touches the billet may tend to feed the billet longitudinally as well as to rotate it and may, indeed, have all its relations between it and the axis of the pass precisely the same as the other roll. The amount of such feed will vary approximately as the cosine of the angle In other words, a base-plane may be' between the axis of the pass and the line of motion of the point of the roll that touches the billet and can'be calculated sufficiently accurately for practical purposes. These relations will now be explained in a concrete instance, as shown in the accompanying drawings, wherein Figure 1 is a plan view of a mill operating under the present invention. Fig. 2 is an end view looking along the axis of the pass. Figs. 3 and 4 are views'of the two rolls, taken at right angles to the pass, so as to analyze the feeding effects of the respective rolls; and Fig. 5 is a part section on the plane 5 5 of Fig. 1.

The bearings and supports of the rolls are omitted, as they are not of the essence of my invention.

As a matter of mechanical convenience I prefer to have the pass horizontal and one of the axes of the rolls horizontal, as these two conditions can be fulfilled without affecting the relations between rolls and billet in any respect. These two conditions merely determine that the base-plane is parallel to the horizon. I prefer to have the angle between the two roll axes about one hundred and twenty degrees and the angles between the line of the pass and the roll-axes each about sixty degrees. The rolls should also be preferably of the same size and shape and rotated at the same angular speed; but, obviously, these relations may be changed, and yet the linear speeds of the rolls on the two sides of the'pass be kept equal, because the linear speed at any point is the product of two factors-namely, the angular velocity of the roll and the radial distance of such point from the axis of the rolland the use of a smaller conical roll to replace one of, say, twice its diameter, must be understood to be the use of an equivalent if due regard be had for the smaller angle which the roll will occupy and the proportional speed required between cooperating rolls of difierent sizes.

The two rolls of conical form may preferably consist of two or three distinct frusta of cones, forming a converging and then diverging pass, or the frusta may merge from one into another insensibly, as well known in the Mannesmann processes.

The roll that has its axis parallel with the chosen base-plane, but raised above the axis of the pass two or three inches, may then be regarded as tending to feed the billet forward by reason of its elevation, or, in other words, by its displacement from such planes. This is shown in Fig. 8. The arrow i represents graphically the direction and linear speed of the roll at the point in contact at the midlength of the pass. Therefore the short arrowf, which is the component of the movement 15 along the pass, which equals 15 cosine A, represents the amount or speed of feed, A being the angle between the axis of the pass and the line drawn to indicate the direction and linear speed of the roll. The axis of the roll 7', on the contrary, is not parallel with the base-plane, but is inclinedskewed, let us supposesix degrees thereto. This appears at about seven degrees in Fig. 2 and about twelve degrees in Fig. 4, owing to-these views being taken at difierent angles to the axis. Let the long arrow tr represent the linear speed and direction of the point of the roll in contact with the billet at the mid-length of the pass. Then,owing to the inclination of the roll-i. 6., the skewing of the rollthis produces a component fr parallel with the pass. Hence fr represents the speed of feed given by the roll 1'. The speeds f and fr if not equal should be made equal by adjustment of either or both rolls. Displacing the roll Z farther above the plane of the pass will increase its feed. Increasing the angle of inclination-i. 6., the skew-of the roll 1' to the said base-plane will increase its feed.

As seen in Figs. 2 and 5, the rolls Z and a do not impinge upon the billet at points exactly opposite, but, on the contrary, owing to the inclination and unsymmetrical disposition of the two rolls the lines-t'. 6., the bands of contact between the two rolls and the billet-are not on diametrically opposite sides of the billet, but about seven degrees less than opposite, by which means a slight tendency to slip downward is produced upon the billet, and this has the beneficial function of holding it firmly but lightly against the guide g, enabling me to dispense with a top guide. Furthermore, it will be seen that the angle between each roll-axis and the pass is still about sixty degrees, and this relation is not dependent on either the elevation or the skewing of either roll to the base-plane.

I am well aware that a pass between parallel or nearly parallel disks has been placed below both their centers to get feed from both rolls, and I am equally well aware that the axis of the pass between two equallyinclined or oblique rolls has been placed below the narrowest point of the pass; but, as described, my invention is distinct from these, in proof of which I submit that in so displacing the path downward the feeding effect of one roll is increased and that of the other decreased, because the axis of the pass then approaches an intersection with one roll-axis equal.

and recedes from the other. Intersection of the axis of a roll with the axis of the pass is the essential condition of no feeding eifect. This is true in all instances, even where the billet and the rolls are cylindrical, for in such case where the axes are parallel they intersect ad infinifum.

In order further to distinguish myinvention from instances wherein a plane passed through the axis of the billet or pass and parallel with one roll-axis is also parallelwith the other rollaxis, I cite for consideration that in such cases the two contact-lines between the respective rolls and the billet will be on diametrically opposite sides of the billet or else the rolling and feeding effect of the two rolls will be un- In such instances an end elevation, looking axially along the pass, will show the two roll-axes projected as lines parallel to each other, just as in my patent above referred to and as in all other Stiefel patents. Under the present invention this will not be the case. Fig. 2 shows that if a plane be passed through the axis of the pass parallel with the axes of either rolls it will make an angle of about seven degrees with the axis of the other roll; but, as is obvious, the displacement, offset, or perpendicular distance between either roll-axis and such a plane parallel to it is or should be exactly equal to the corresponding displacement of the other roll from its said parallel plane. The angles and other relations of each of the two rolls when separately studied in respect to the axis of the pass are identical.

I claim as the novel and characteristic features of the present invention the following:

1. In apiercing or expanding mill, the combination ofa mandrel,two substantially equal obliquely-rollin g rolls and a guide mounted to form a pass between the rolls, the said rolls being unsymmetrically placed in respect to the axis of the pass, one of the roll-axes lying at a slight angle to an imaginary plane parallel to the other roll-axis and containing the axis of the pass, and the axis of the other roll being displaced from the said plane, whereby with reference to such plane one roll feeds by inclination or skew and the other by displacement or elevation.

2. In a piercing or expanding mill, the combination of a mandrel,two substantially equalfeeding obliquely-rolling rolls, and a guide forming a pass between the rolls, the said rolls being unsymmetrically placed in respect to the axis of the pass, one of the roll-axes being inclined in respect to an imaginary plane containing the pass-axis and parallel with the axis of the other roll, and the axis of said other roll being displaced from said imaginary plane, whereby with reference to said plane one roll feeds by reason of its obliquity thereto and the other by its displacement therefrom.

3. In a piercing or expanding mill, the combination of a mandrehtwo substantially equalfeeding obliquely-rolling rolls, and a guide 4. In a piercing or expanding mill, the combination of a mandrel,two substantially equalfeeding obliquely-rolling rolls, and a guide forming a pass between the rolls, the said rolls being unsym metrically placed in respect to the axis of the pass, one of the roll-axes being inclined in respect to an imaginary plane containing the pass-axis and parallel with the axis of the other roll, and the axis of said other roll being displaced from said imaginary plane, and the lines of contact between the rolls and the billet being unsymmetrical instead of opposite, whereby the billet is pressed toward the guide, substantially as set forth.

Signed this 13th day of March, 1900, at New York, N. Y.

JOHN H. NICHOLSON. Witnesses:

EDWARD A. FRESHMAN, HAROLD BINNEY. 

